Davis Stores sells clothing in 15 stores located around the southwestern United States. The managers at Davis are considering expanding by opening new stores and are interested in estimating costs in potential new locations. They believe that costs are driven in large part by store volume measured by revenue. The following data were collected from last years operations (revenues and costs in thousands of dollars)

Store	Revenues	Costs
101	$4,280	$4,484
102	2,407	3,254
103	6,008	5,451
104	4,342	4,448
105	3,184	4,216
106	4,383	3,949
107	7,074	5,299
108	2,049	3,274
109	6,316	5,408
110	3,768	3,499
111	4,246	4,629
112	5,140	3,560
113	3,732	3,096
114	5,537	5,015
115	3,024	3,256

Simple regression results from the data of Davis Stores are as follows

Equation:
Store costs = $2,061.9 + (Revenue 48.7%)
Statistical data
Correlation coefficient	0.828
R2	0.685

Required:

a. Estimate store costs for a store with revenue of $4.3 million.

b. What percentage of the variation in store costs is explained by the independent variable?